What this SIRIUS contactor is and what it does
The Siemens 3RT2037-3XF44-0LA2 is a size S2 SIRIUS contactor rated for 65 A at 480 V and 52 A at 600 V, making it a solid pick for switching motor loads in industrial control panels up to that current range. The coil is 110 V DC with spring-type terminals — no screw torque to verify, just strip and push. Mounts via screw or snap-on onto 35 mm standard mounting rail per DIN EN 60715, so it drops into any standard European panel layout.
Panel fit and clearances
Dimensions are 55 mm wide, 114 mm tall, 178 mm deep — the depth is the main thing to check against shallow enclosures. Minimum clearances: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side for heat dissipation and arc flash. Mounting position is flexible — +/-180° rotation on a vertical surface, and can tilt forward/backward by +/-22.5° on vertical mounting.
Switching performance and ratings
Rated for AC-4 duty at 200 operations per hour maximum — that's the heavy inching/jogging cycle, not just continuous running. Arcing time is 10 to 20 ms, and the DC coil dropout time is 30 to 55 ms; the inrush current peak at coil pick-up is 1.5 A. Main contact ratings at 110 V DC: 1 A; at 220 V DC: 0.3 A; at 690 V: 1 A — these are the DC switching limits, not the AC motor ratings.
Lifecycle and sourcing posture
Operating temperature range is -40 to +70 °C; storage range is -55 to +80 °C, which covers most industrial environments.